Tesla had made an offer to buy SolarCity in June, but a deal was not certain because SolarCity had formed a special committee to review the offer.

The companies said SolarCity stockholders would receive 0.110 Tesla common shares for every share held, valuing SolarCity at $25.37 per share based on the five-day volume weighted average price of Tesla shares as of Friday.

Based on Tesla’s Friday close, the offer works out to $25.83 per share—a 3.4% premium to SolarCity’s last closing price.

SolarCity’s shares, which had risen about 26% since Tesla first made the offer on June 21, were down 3.75% at $25.70 before the bell on Monday. Tesla shares were up 0.51% at $235.99.